title: Retention of the in vitro radiosensitizing potential of gemcitabine under anoxic conditions, in p53 wild-type and p53-deficient non-small-cell lung carcinoma cells.
abstract: OBJECTIVE
  Whereas radiosensitization by gemcitabine is well studied under normal oxygen conditions, little is known about its radiosensitizing potential under reduced oxygen conditions. Therefore, the present study evaluated the impact of anoxia on gemcitabine-mediated radiosensitization.
  
  
  METHODS
  The clonogenic assay was performed in three isogenic A549 cell lines differing in p53 status (24 h, 0-15 nM gemcitabine, 0-8 Gy irradiation, normoxia vs. anoxia). Using radiosensitizing conditions, cells were collected for cell cycle analysis and apoptosis detection.
  
  
  RESULTS
  Whereas wild-type p53 A549-LXSN cells were more sensitive to radiation than p53-deficient A549-E6 cells, both cell lines showed similar radiosensitization by gemcitabine under normoxia and anoxia. Independent of p53 functionality, gemcitabine was able to overcome anoxia-induced G(0/1) arrest and established an (early) S phase block in normoxic and anoxic cells. The percentage early and late apoptotic/necrotic cells increased with the gemcitabine/radiation combination, with a significant difference between A549-LXSN and A549-E6.
  
  
  CONCLUSIONS
  This study is the first to show that gemcitabine retains its radiosensitizing potential under low oxygen conditions. Although radiosensitization was observed in both p53 wild-type and p53-deficient cells, p53 status might influence induction of apoptosis after gemcitabine/radiation treatment, whereas no effect on cell cycle progression was noticed.
authors.affiliation: Laboratory of Cancer Research and Clinical Oncology, Department of Medical Oncology, University of Antwerp, Wilrijk, Belgium. An.Wouters@ua.ac.be
authors.forename: An
authors.initials: A
authors.lastname: Wouters
authors.forename: Bea
authors.initials: B
authors.lastname: Pauwels
authors.forename: Hilde A J
authors.initials: HA
authors.lastname: Lambrechts
authors.forename: Greet G O
authors.initials: GG
authors.lastname: Pattyn
authors.forename: Johan
authors.initials: J
authors.lastname: Ides
authors.forename: Marc
authors.initials: M
authors.lastname: Baay
authors.forename: Paul
authors.initials: P
authors.lastname: Meijnders
authors.forename: Marc
authors.initials: M
authors.lastname: Peeters
authors.forename: Jan B
authors.initials: JB
authors.lastname: Vermorken
authors.forename: Filip
authors.initials: F
authors.lastname: Lardon
mesh_terms: D000704:Analysis of Variance; D017209:Apoptosis; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000532:radiotherapy*; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D009336:Necrosis; D011836:Radiation Tolerance / Q000187:drug effects*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D016196:S Phase / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency; D000093542:Gemcitabine
chemical_list: D011838:Radiation-Sensitizing Agents; D016159:Tumor Suppressor Protein p53; D003841:Deoxycytidine; D000093542:Gemcitabine